The present invention relates to an ultrasonic instrument for use in interventional procedures employed in surgical and medical investigations, treatment or diagnosis, in research and in related fields.
In procedures involving the insertion of an instrument into a human or animal body, it is often necessary for the position of the instrument to be known accurately. The use of ultrasonic instruments, in particular imaging scanners, to guide the insertion of surgical instruments such as puncture needles or catheters during invasive medical procedures is known. The imaging system usually relies on detection of passive echos from the instruments, but more recently techniques have been developed in which an ultrasonic transducer is located on the end of the instrument to provide an "active" detection system. The ultrasonic wave emitted by the imaging system is detected by the transducer, and an electrical signal is conveyed back to the imaging system, or the transducer emits an ultrasonic signal for detection by the imaging system. For more general information reference can be made to U.S. Pat. No. 3,556,079 and U.S. Pat. No. 4,249,539. GB-A-2157828 describes an instrument in which the ultrasonic sensor is connected to a detection circuit by a pair of solid conductive paths. This requires quite complicated and accurate fabrication techniques.